Indoor facilities employing freezing, cooling or refrigeration loads can present significant dehumidification problems. Indoor ice arenas and supermarkets present particular concerns. In ice arenas, the ice rink surface is maintained at subfreezing temperatures by a liquid secondary cooling loop, customarily utilizing glycol as the liquid refrigerant. The ice surface and spectators and participants generate a substantial humidity load that can result in undesirable condensation, particularly under extreme environmental temperature and humidity conditions and to the detriment of equipment and attendant personnel comfort. Similarly, the freezer, cooler, and refrigeration equipment, and customers in supermarkets generate substantial humidity loads creating like equipment and personnel problems.
An improved energy efficient air handling system for maintaining humidity levels in ice rink facilities is disclosed in my prior patent, U.S. Pat. No. 6,321,551. Therein, the process air stream is cooled and dehumidified at a dehumidifier unit serially connected with the ice rink coils, and reheated by a waste heat exchanger to a low return temperature. The system significantly reduces the parasitic heating by the return air resulting in dramatically lowered utility costs, and handles substantial dehumidification loads.
There is a current trend, however, at the state and municipal regulatory level to mandate increases in the amount of exterior make up air in the return air flow to the above facilities. This added make up air volume establishes an incremental dehumidification burden that can exceed the capabilities of the existing equipment. To avoid the need for upsizing the equipment and thus increasing capital and operating costs, it would be desirable to utilize the thermal benefits of the patented system while handling the increased dehumidification requirements.